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Delamintion of fiberglass sidewall

Max Death

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First a bit of history. Had a leak just in front of bedroom slide for a day or two before I found it and repaired it. This was almost four years ago. Everything seemed fine.

The last two times I have hitched up I now have a six inch wide by eight inch high area of the fiberglass sidewall that seems to have delaminates. It has obviously rubbed on the channel at the bottom until there is no longer any fiberglass to set in the channel. When the rv flexes a section six inches by eight inches pops out over the bottom channel of the fifth wheel overhang. When I press against it it goes back into place and feels solid as if the underlayment is solid.

I have just been in a park and am currently in one that does not allow work on RVs so have not been able to do more then cursory analysis.

My questions are.

If the wall is solid and it just needs glued, what type of glue would be best? Have heard epoxy and also gorilla glue.

Should I attempt to replace the fiberglass that has been worn away?

Would most of you attempt this or would you take it to a shop?

I myself could do it just not real familiar with fiberglass repair.

Should be in a park in Lake Havasu in October where I can work on it.

Thanks for any replies

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Delamination is a very frustrating problem and fixing it isn't a "one size fits all" project since glue that works on one RV's components can fail or cause damage on a different brand. Best to contact your RV's manufacturer and ask about the glue to use to repair the sidewall.


It looks like you could remove the fiberglass trim piece from the bottom edge there which would give you better access to the problem site. If the worn-off lip was part of the trim a replacement piece might solve the problem there too. Worst case you'd have it in an easier location to work while you made a replacement lip with a fiberglass repair kit.


To fix the delaminated area, if it is just a glue failure, you can stuff in more glue and make pressure clamps to hold it firmly together while the glue cures. What we have seen used was a piece of 3/4 plywood on top of a section of high-density foam rubber to apply the pressure evenly to the area. That was clamped down using several 2x4s on each side of the RV and ropes that were tightened to compress the foam pad. Do pad both sides where the 2x4s contact the rig, they may well leve visible dents if placed directly on the siding. You also do not want to glue the pad to the RV if at all possible so if leakage/seeping is likely add a layer of something that the glue won't stick to under the pad, possibly a layer of mylar rescue blanket, depending on the glue choice.


If there is rot or mold in there then you need to stop it before going further, I'm no expert on product choices there so I won't offer suggestions.

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Earlier this summer a RV'er we were hosting with had a similar issue. The fiberglass panel on the bottom of the bedroom slide split open due to rubbing on 2 channels when the slide was extending and retracting. Our solution was to first caulk the open split to get it sealed off. We then got 2-10ga stainless steel plates 8" wide and 24" long which we placed over the slit opening so the channel would now rub on the SS plates. We held the SS plates in place with glue and screws along the outside edge. This was under the bedroom slide so the SS plates are not seen for the most part unless you got under the slide and looked up.


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I've been looking at that photo and what I want to know is does it move when you are hitching and unhitching. If so you may have other problems besides the wall siding being deaminated, you may have a frame Flex problem causing the siding to move. I've been through this on both sides of our trailer, I had to peal the siding back and repair water damage and fix a engineered problem that caused the problem in the first place.


Looking at your siding backing it looks like the plywood has some water damage, not knowing if you trailer is wood or aluminum framed it's hard to tell you how to repair it.


I tried to repair mine without removing the siding and it failed, I had to get in there and fix it permanently, lots of rotted wood because of the way it was built, just shoving some glue in there isn't going to work.


For a temp fix get some Eternabond tape to seal out the water, it will flex and stay in place.



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  • 1 month later...

Just an update to let everyone know what happened with this problem. Took filon off the front of fifth wheel. All of the frame was in good shape. Removed front cap. Manufacturer had forgot to place 2x4 between frame and a wall stud. Placed 2x4 where it should have been. Checked other side it was fine. Built up fiberglass then glued and clamped. Put everything back together. Now fixed.

Should call and rant at RV manufacturer but won't.

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Thanks for the report. I wonder if the 2x4 was forgotten, or just left out, but we won't ever know that for sure. I stay out of this type of discussions as so far I've not had the experience of dealing with a delam problem, and hope that I never do.

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That link does NOT show a proper repair procedure. http://epoxyworks.com/wp-content/uploads/2014/07/Fig1.jpg This is how it should be done.

I don't know much about repairing fiberglass, would what you linked to repair what is shown in the picture? Only reason I replied with that aircraft link was trying to provide some online information.

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I stand corrected. I confused the sandwich laminate picture with the solid laminate picture. As shown on both sites the first ply must be full length as shown with each succeeding ply a little smaller till you build to the original thickness. The 12:1 scarf ratio is very important.


Thanks for pointing that out RayIn

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